I. Field
The present disclosure relates generally to communication, and more specifically to techniques for performing channel estimation in wireless communication.
II. Background
A multi-carrier communication system employs multiple carriers for data transmission. These multiple carriers may be obtained via Orthogonal Frequency Division Multiplexing (OFDM), Single-Carrier Frequency Division Multiplexing (SC-FDM), or some other modulation techniques. OFDM and SC-FDM partition the system bandwidth into multiple (K) orthogonal carriers, which are also referred to as subcarriers, tones, bins, and so on. Each carrier may be modulated with data. In general, modulation symbols are sent in the frequency domain with OFDM and in the time domain with SC-FDM.
A multi-carrier system may transmit data and pilot in time-frequency units referred to as cells. A cell is one carrier in one symbol period and may be used to send one modulation symbol. A transmitter processes (e.g., encodes, interleaves, and modulates) data to generate data symbols and maps the data symbols on data cells. The transmitter typically maps pilot symbols on pilot cells that may be distributed across time and frequency. The transmitter then processes the data and pilot symbols to generate a modulated signal and further transmits the signal via a wireless channel. The wireless channel distorts the transmitted signal with a channel response and also degrades the signal with noise and interference.
A receiver receives the transmitted signal and processes the received signal to obtain received symbols. For coherent data detection, the receiver estimates the response of the wireless channel based on received pilot symbols and derives a channel estimate. The receiver then performs data detection on received data symbols with the channel estimate to obtain data symbol estimates, which are estimates of the data symbols sent by the transmitter. The receiver then processes (e.g., demodulates, deinterleaves, and decodes) the data symbol estimates to obtain decoded data.
The quality of the channel estimate has a large impact on data detection performance and affects the quality of the data symbol estimates as well as the reliability of the decoded data. This may be especially true for certain operating environments such as, e.g., high mobility scenarios where the wireless channel response may change rapidly.
There is therefore a need in the art for techniques to derive a high quality channel estimate.